Image recording apparatus



' H. E. HAYNEs IMAGE RECORDING APPARATUS y Filed Nov. 4, 1949 Oct. 7, 1952 dQTTORI'; EY I Patented Oct. 7, 1952 'Harold E.l Haynes, Audubon, N. J., assignor toy Radio Corporation ofl America, a corporation of.4 Delawaref- Application Noventa 4, 1949, serial No. 125,538

The present inventionL relates to the photographic recording of images, and" more particularly, although not,necessarilyexclusively, to a novel arrangement for controlling apparatus for photographically recording recurring images produced by television methods whereby a single image record may be obtained at will.

It is desirable toeord'images of transmitted television,programs'for future use as program material, as Wellasffor preservation to serve as a record of transmitted subject matter. It is also desirable conveniently to obtain a record, of a single image frame for test purposes or the` like.

In applicants copending application,"`Serial No. 114,420,1i1ed september '1, 1949 there is .dis`

closed a system for keying a television image on and off at precisely `controlled instants relative to the vertical and horizontal `deflections of the cathode ray beam Vof, an image producingl cathode ray tube by employment of electronic` counting apparatus which is interlocked in operation with the rate of production of television images.y `The mechanism of the camera' used for recording purposes serves to' move 'the film at intervals vand to provide a non-critically `timed initiating pluse.

In accordance withl the present invention, an arrangement is provided for operating the recording apparatus in such a manner that only a single image is produced by the cathode ray tube While a single nlm frame is maintained in position for exposure.` One important feature of the apparatus embodying :the present invention is that means are incorporated for preventing recurrence of the operating cycle of the electronic controlling mechanism which Would spoil the record of the single image to be taken for test purposes.

The principal aimof the present invention is to provide novel control apparatus for obtaining va single nlm frame recording by apparatus .which 4 1 claim. (ci. 17a- 7.4)

` the single sgresrlows," diagrammauqaumyabtherein.

paratus for obtaining a continuous photographic record ofV television images Withr the novel arrangement of the present invention included Referring to thedraxying," vreference character I0 indicates a television image producing device,

shown illustratively asa cathoderay tube, upon the target end I2 of which television images are produced by the impingementof a deflected scanning beam I4. vBeam Ideflectingjmeans'including deflection yoke I6 cause the image mod* ulated beam I4 to be swept over the tubeend'v I2 `along spaced scanning lines. In accordance by each complete sweep of the beam I4.

with the usual practice, "alternate linesare traced The electrode structure of thetube'll includes va. cathode I8 and a grid v20. VHImage'signals Yare applied to the grid 2`in the usualmanner'from 0. tion disclosed in the above mentioned copendlng normally functions cyclically to provide a sef nection with the accompanying drawing in which Yso avideo amplifier 2l. Compositevideo and A'sync signals,A such as are obtained from the second detector `ofa television .receiver (not shown),

are applied to the video amplifier and to async f' separator 22;

The output of the sync separator is employed to control horizontal and vertical deiiection generators 24 and 25. The foregoingfis the usual arrangement in television vreceivers having a cathode ray tube serving as an image producing device and is'readily adapted forrecording purposes in accordance with the invenapplication. l,

The images to be recorded are photographed on a film strip 4I by a camera comprisingan intermittent mechanism 46 .which pulls ther :lm through the film gate 48 at the rate, for example, of twenty-four film frames per second. The intermittent mechanism 46 may, for example, `be driven by a motor 5| whichis of the type operating at substantially constant speed. Gearing 52, which is indicated conventionally, is provided-to v.suit the speed of operation of theintermittent mechanism 46 to the normal speed of the'motor 5I. A shaft 54 is driven from the gearing 52so that it rotates in synchronism with operation of the pull-down mechanism 46. When the pulldown mechanism has operated to advance lthe `fi1m.4I to a new frame position, a commutator 56 of insulating material having a conductive segment 58 closes an electrical circuit including a slide contact or brush 59.v f.

Generally, in operation of the arrangement shown by Fig 1 it is required that one, complete television image be photographed upon each motion picture film frame. It is further required.

more. .in detail hereinafter'.

An electronic counter 7|, which may comprise l, a number of multivibrators or nip-flop circuits,

is shown in block form since a .detailed disclosure y of its operation is not necessary -for an understanding of the present invention.

The control section of the apparatus includes a normally open key or switch ."1'2 which 'i'sito be operated to obtain photographic exposure,y in` accordance with the present invention, of a single frame only of the television images being produced'bythe tube ,|0. The .function f .theswitch 12 'and .its .associated circuits will `bedescrib'ed .Horizontal sync signals, which occur at the rate of 15,750 per .secvond in accordance with present day practice, are obtained in the illustrative example from the sync separator -22,and are applied over a conductor`19 to the .control grid 8| of an amplifier 4tubev82 by way of 4a coupling condenser 83 and a potentiometer 84. 82 is coupled to the gridfSE of a gating amplifier tube B8. The` anode of the gating amplifier is connected to the counter by way o f a condenser 85. The gating eiTect of the lgating amplifier is controlled by means of a tube 9|, which may bea gas discharge tube of the 2D21 type. -The signal grid 92 of the tube 9| is connected -through a resistor 93 to the contact brush 59 by way of a conductor 94. made through a resistor 95 to a source (not shown) of negative potential. This sourc'e vis or may be 'connected-in a conventional mannerto a circuit reference point such as ground. One

contact, for example, Vthe .movable contact,. of

the'switch 12 is connected through a resistor 90 to the end of the resistor 95 opposite the grid of the tube 9|. A condenser l0 is connected between the movable contact of the switch 12 and the end of the resistor nearest the grid 92.`

The remaining contact of the switch I2 is grounded. lit will be noted that the source (not shown) of D. C. voltage is effectively in series circuitl which includes the switch 12, the condenser and the resistor 95. When the switch is closed, .the voltage of the source appears across the series combination of condenser 10 and resistor '95, and a charging current flow. However, at the instant the charging current commences, the end of the resistor 95 nearest the grid is more positive than with the switch open and the condenser discharged. As the condenser becomes charged, the charging currentsubstantiallyy ceases and since no current then i'lows in resistor 95, the grid 92 is maintained negative. After the switch is opened, the condenser control |06 which provides a conductive path A connection is also 4 except after completion of a counting operation by the counter 12.

Closure of the contacts 58 and 59 causes the tube 9| to become conductive, as indicated above, applying sufiicient screen grid voltage to gating amplifier 88 to cause it to transmit horizontal sync pulses, which causes the counter to operate. An initial multivibrator stage (not shown) of the counter p'rovides a change in voltage in the positive direction which is applied through a condenser ||4 and a resistor ||6 to a blanking device H8. The blanking device ||8 funcftions as -vasou'rce of cathode blanking bias for .the cathode ray tube l0 which is supplied over a .conductor 'I glto the cathode |8 of the cathode ray tube |0. 'Blanking bias is removed from the tube I0 at this time.

Vi/'hen the count is completed the voltage in av'conductor |4| rises in a positive direction The output ofthe tube' lines as 'determined by the counter 1|.

which causes operation of the reset device |34. A conductor |65 provides a resetting voltage from the reset. 'device |34 to the counter 7|.

The conductor |`4| isv also connected to the blanking and gating control device |06. rThis device may be electronic vin nature and serves to "-op'en'the circuit of the gas discharge tube 9| and also to 'cause the blanking device ||8 to blank the be'ar'n'in .the tube I0. The device |86 Ymay "comprise 'one or more vacuum tubes (not shown) which A'may be rendered non-conductive.

The 'systemde'scribe'd above, in sufficient detail to form a setting'ior the present invention, operates under control of the commutator 56 to 'record' two television fields on each lm frame. Each iilm exposure period4 includes exactly 525 This splice 'on alternate lm frames between the beginning of exposure of. a film frame from one television frame v'and the end of exposure from the next television frame is precisely obtained so that scanning lines are neither lost nor duplicated.

It is essential when obtaining exposure of a single frame for test or other purposes to limit operation 'of the apparatus to only one exposure cycle, If 'a second exposure cycle is initiated, the te's'texposure is worthless since the film is not'advanced to a new area as it would be with the system operating to produce successive exposures under control of the commutator 56.

AIn normal operation the contacts 58 and 59 are connected -together once for each pull down 'cycle of the camera, and reopened before the end of exposure for that frame.

For the present single-frame exposure purposes, the above described resistor and condenser 18 cooperate in their connection to the grid 92 of tube 9| to insure against accidental recycling f the equipment.

l Operation of the switch 12 and its associated elements to provide a single frame record. in accordance with' the present invention will now be described.

Withv the' switch 12 open,`the grid 92 of the tube' 9| is biased negatively thereby preventing firing of this tube. The condenser 1U has been discharged through the resistors 98 and 95 and both of it's vterminals are hence at -8V1, the bias-supply potential. When the switch 'I2 is closed, the potential at the terminal of the condenser 10 connected-to the resistor 90 is raised in the positive direction from the negative value corre'spondingto the negative bias applied to the grid 92,to ground or zero potential. Assuming, by' Way 0f example that the end of the resistor 95 opposite tothe resistor 93 and the grid 92 is connected to -8 volts as indicated on the drawing, a positive-going pulse of eight volts is thus fed through the condenser 'i9 to grid 92 to re the tube 9i. At the end of a period of time, determined by the counter 1l, the tube 9| is extinguished by the blanking and gating control device |06. This period of time is it@ second, assuming operation of the tube l0 in accordance with present day television standards. The tube 9| does not refire since by this time the condenser 10 has charged through resistor 95 to substantially 8 volts, in the illustrative example, even if the switch 12 is still closed. Consequently the tube 9| cannot be fired again until the switch l2 is opened long enough to permit the condenser 'l0 to discharge.

The values of the resistors 90 and 95 and the condenser 10 are not critical. C'onvenient values are: resistor 95:4700 ohms, resistor 90:1 megohm, and condenser 10:0.2 mi. for the condenser and 1 megohm for the resistor 90. This gives a firing pulse of 1 millisecond time constant (RssXCvn) and the combination of Rsm and Cro will permit exposing another frame within about one second after the switch 72 is opened. When the tube 9| is a type 2D2l, the resistor 93 may have a value of 12,000 ohms.

What is claimed is:

A recording system for recording television images comprising a cathode ray tube and means for causing operation of said tube to produce images, said means including a sync pulse separator, a camera for photographing said images, an electronic counter, means to feed sync pulses to said counter from said sync pulse separator comprising a vacuum tube having at least a cathode, an anode, a control grid, and a screen grid, a gaseous discharge tube, means whereby said gaseous discharge tube varies the voltage applied to said screen grid, means including a connection from said camera whereby said gaseous discharge tube acts normally under control of said camera to control the feeding of sync pulses to said counter, electronic means capable of completing a circuit and being effectively in series with said gaseous discharge tube, means for controlling said electronic means from said counter to interrupt its conductivity and hence the conductivity of said gaseous discharge tube, and additional means for controlling said gaseous discharge tube comprising a manually operable switch connected to said connection from said camera, a resistor and capacitor combination eiectively in series with said switch and with a source of D. C. biasing voltage, and a discharge resistor shunting said resistor and capacitor.

HAROLD E. HAYNES.

REFERENCES CITED 'The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,979,054 Scheer Oct. 30, 1934 2,148,145 Ward Feb. 21, 1939 2,474,841 Hatfield July 5, 1949 2,493,412 Lange Jan. 3, 1950 2,504,734 Schmidling Apr. 18, 1950 2,509,910 Dike May 30, 1950 2,545,257 Bryan Mar. 13, 1951 2,558,969 CI'Oy July 3, 1951 

